Have you done multiple valve body replacements and found they didnt work?
Have you changed your transmission and had it damage again in a few days or not work at all?

The reason is simple.
The replacement valve body was most likely fine, so was the replacement transmission.
However, my people suffer from lack of knowledge.

In most US spec Nissans, especially the ones with CVT transmission, each time a valve body/transmission is replaced, the data (EEPROM) on the current TCM must be erased (flashed) because it already has data from the former valve body/transmission written on it.

For your replacement to work, the TCM must be able to recognize it and synch with it.
Therefore, a TCM EEPROM erase procedure MUST be followed.
After this is done, a simple procedure to write the data from the replacement valve body/transmission to the TCM must also be followed for all to be well.

Please take note!